Prioritize Corn Harvest by Checking Stalk and Ear Rots Now

By Andi Anderson

Purdue University specialists are encouraging Indiana corn growers to scout fields now for stalk and ear rots so harvest plans can be set by risk. Early evaluation helps avoid stand loss from lodging and reduces the chance of mycotoxin issues at the bin.

Stalk rots weaken plants and can be triggered by diseases or non-disease stresses like heat and drought.

When leaf area is lost to stress or foliar disease, plants “rob” carbohydrates from the lower stalk to finish grain fill, leaving stalk tissue brittle and prone to lodging. Common stalk-rot culprits include anthracnose, charcoal rot, diplodia, fusarium, gibberella, pythium, and some bacterial infections.

Use two quick field checks across the farm:

• Pinch Test: Squeeze the stalk between the lowest two internodes. If it collapses, it fails.
• Push Test: Gently push plants to about a 30-degree angle. If they do not spring back upright, they fail.
• Threshold: If 10% or more of plants fail in representative checks (20 plants in at least five areas), prioritize that field for early harvest to reduce lodging losses.

Scout ears as well. Several ear rots can produce mycotoxins of concern:

• Aspergillus → aflatoxin
• Gibberella → deoxynivalenol (DON/vomitoxin) and zearalenone
• Fusarium → fumonisins
• Penicillium (and sometimes Aspergillus) → ochratoxin

If ear rot is present, test grain lots for mycotoxins using proper sampling (multiple, well-mixed sub-samples). After harvest, dry grain quickly to below 15% moisture and store cool and dry to slow fungal growth and limit toxin accumulation.

Purdue’s Crop Protection Network provides clear photo guides for identifying stalk and ear rots, plus a step-by-step sampling and testing reference and a directory of professional labs. Purdue will also conduct a 2025 survey of Indiana grain for mycotoxins to improve forecasting; growers with suspect fields are invited to participate.

Bottom line: scout now, rank fields by risk, harvest the weakest first, dry fast, and store cool. These steps protect standability, grain quality, and livestock feed safety as harvest approaches.

Photo Credit: purdue-university